Association of childhood cancer with factors related to pregnancy and birth.

BACKGROUND: It has been hypothesized that risk factors of childhood cancers may already operate during the prenatal and neonatal period. Results of previous epidemiological studies have been inconsistent. METHODS: During 1992-1997 a large case-control study on childhood cancers and a variety of potential risk factors was conducted in Germany. Cases were ascertained by the German Childhood Cancer Registry. Each case was matched to a population-based control of the same age and gender, sampled from the district where the case lived at the date of diagnosis. For the analyses, 2358 cases and 2588 controls were available. RESULTS: Risk of childhood acute leukaemia increased with maternal age < or =20 years at time of delivery (odds ratio [OR] = 1.9, 95% CI: 1.1-3.2), lower (<2500 g: OR = 1.7, 95% CI: 1.1-2.8) and higher birthweight (>4000 g: OR = 1.4, 95% CI: 1.0-1.8, P < 0.05), and hormonal treatment because of infertility (OR = 1.6, 95% CI: 1.0-2.5, P < 0.05). No associations were seen for parental smoking habits, maternal alcohol consumption during pregnancy and fetal losses. Parity was associated only with subgroups of acute leukaemias. Regarding non-Hodgkin's lymphoma we observed an elevated OR for lower birthweight and heavy maternal smoking during pregnancy (>20 cigarettes/day) and a decreased OR for children with one or two siblings. Only a few significant findings were seen for the different groups of solid tumours. CONCLUSIONS: Overall, only weak associations were identified and the evaluated risk factors operating during the neonatal and prenatal period account at most for only a small proportion of childhood cancers.     

Risk factors in term children for visual impairment without a known prenatal or postnatal cause

Risk factors were studied for visual impairment in children without known pre- or postnatal cause, for a decrease of visual acuity. Children born at term 1979-98 and with a visual impairment were identified from the Swedish Register of Visually Impaired Children and data were linked with the Swedish Medical Birth Registry. Maternal characteristics such as maternal age, parity, maternal smoking habits in early pregnancy, maternal education, nationality, and subfertility were studied as well as maternal diagnoses such as pre-eclampsia, prolonged second stage of labour, abruptio placentae, and placenta praevia. Mode of delivery was analysed as well as birthweight, and birthweight in relation to gestational age. Abruptio placentae turned out to be the strongest risk factor (OR = 8.24 [95% CI 5.01, 13.51]). Smoking did not give a statistically significant increased risk. There is an increased risk with breech delivery (OR = 2.01 [95% CI 1.28, 3.17]). Pre-eclampsia was associated with an increased risk (OR = 2.22 [95% CI 1.46, 3.38]). There is also an increase in risk at low birthweight and small-for-gestational-age as well as birthweight > 4 kg and large-for-gestational-age. In this study we found that risk factors particularly worth noticing in term children with a presumed perinatal cause of visual impairment are abruptio placentae, pre-eclampsia, excessively low as well as excessively high birthweight, and breech delivery, a fact worth noticing in current discussion on risks, advantages or excessive exploitation of caesarean section.     

Determinants of developmental delay in infants aged 12 months

The aim of this study was to determine which demographic, maternal, obstetric and postnatal variables were associated with achievement of developmental milestones at the age of 12 months in term infants. Mothers and babies were enrolled in the Auckland Birthweight Collaborative Study shortly after birth. All infants were full term (gestation >or= 37 weeks). Approximately half of the sample were small for gestational age (SGA = birthweight 10th percentile). A maternal interview was conducted soon after birth. Phase 2 of the study occurred 12 months later when mothers were sent a postal questionnaire requesting information about the child's health and development during the first year of life using the Denver Prescreening Developmental Questionnaire. Seven hundred and forty-four (85.4%) European mothers returned the postal questionnaire. SGA children were not at increased risk of developmental delay at 12 months of age. In a sample representative of New Zealand European children, after adjustment for the effects of potential confounders, maternal smoking during pregnancy (OR = 2.1 [95% CI 1.1, 4.0]), maternal smoking during the first year of life (OR = 1.9 [95% CI 1.0, 3.8]) and low levels of satisfaction with parenting (OR = 2.4 [95% CI 1.1, 5.2]) were associated with significantly increased risk of developmental delay. In the subgroup of SGA children, maternal smoking during pregnancy (OR = 2.9 [95% CI 1.4, 6.2]), high levels of stress associated with parenting (OR = 2.2 [95% CI 1.2, 4.0]), and low levels of satisfaction with parenting (OR = 4.3 [95% CI 1.3, 13.5]) were significantly associated with developmental delay after adjustment for the effects of potential confounders. In conclusion, maternal and postnatal factors were better predictors of developmental delay than demographic variables.     

Maternal cigarette smoking and invasive meningococcal disease: a cohort study among young children in metropolitan Atlanta, 1989-1996

OBJECTIVES: This study assessed the association between maternal cigarette smoking during pregnancy and the risk of invasive meningococcal disease during early childhood. METHODS: Using a retrospective cohort study design, cases from an active surveillance project monitoring all invasive meningococcal disease in the metropolitan Atlanta area from 1989 to 1995 were merged with linked birth and death certificate data files. Children who had not died or acquired meningococcal disease were assumed to be alive and free of the illness. The Cox proportional hazards analysis was used to assess the independent association between maternal smoking and meningococcal disease. RESULTS: The crude rate of meningococcal disease was 5 times higher for children whose mothers smoked during pregnancy than for children whose mothers did not smoke (0.05% vs 0.01%). Multivariate analysis revealed that maternal smoking (risk ratio [RR] = 2.9; 95% confidence interval [CI] = 1.5, 5.7) and a mother's having fewer than 12 years of education (RR = 2.1; 95% CI = 1.0, 4.2) were independently associated with invasive meningococcal disease. CONCLUSIONS: Maternal smoking, a likely surrogate for tobacco smoke exposure following delivery, appears to be a modifiable risk factor for sporadic meningococcal disease in young children.     

Maternal exposures to hazardous waste sites and industrial facilities and risk of neural tube defects in offspring

PURPOSE: We examined the relationship between maternal proximity to hazardous waste sites and industrial facilities and neural tube defect (NTD) risk. METHODS: Texas Birth Defects Registry cases were linked with their birth or fetal death certificates; controls (without defects) were randomly selected from birth certificates. Distances from maternal addresses at delivery to National Priority List (NPL) and state superfund sites and Toxic Release Inventory (TRI) facilities were determined for 655 cases and 4368 controls. RESULTS: Living within 1 mile of an NPL or state superfund site was not related to NTD risk (adjusted odds ratio [OR] = 1.0; 95% confidence intervals [CI] = 0.6, 1.7). Living within 1 mile of a TRI facility carried a slight risk (adjusted OR = 1.2; 95% CI = 1.0, 1.5). The effect was highest among mothers 35 years and older (OR = 2.7; 95% CI = 1.4, 5.0) and among non-Hispanic white mothers (OR = 1.8; 95% CI = 1.1, 2.8). CONCLUSIONS: Hazardous waste sites posed little risk for NTDs in offspring. Close proximity to industrial facilities with chemical air emissions was associated with NTD risk in some subgroups. Further investigation is needed to determine if the effects are real or due to unresolved confounding or bias.     

Disparities in the prevalence of cognitive delay: how early do they appear?

Cognitively delayed children are at risk for poor mental and physical health throughout their lives. The economically disadvantaged and some race/ethnic groups are more likely to experience cognitive delay, but the age at which delays first emerge and the underlying mechanisms responsible for disparities are not well understood. The objective of this study was to determine when sociodemographic disparities in cognitive functioning emerge, and identify predictors of low cognitive functioning in early childhood. Data were from 7308 singleton and 1463 multiple births in the Early Childhood Longitudinal Study‐Birth Cohort (ECLS‐B), a nationally representative cohort of children born in the USA in 2001. Multiple logistic regression analyses examined associations between sociodemographic characteristics and low cognitive functioning at 9 and 24 months, and tested whether gestational and birth‐related factors mediate these associations. Sociodemographic characteristics were statistically significant predictors of low cognitive functioning among singletons at 24 months, including the three lowest quintiles of socio‐economic status [lowest quintile, odds ratio (OR) = 2.7, 95% confidence interval [CI][1.7, 4.1]], non‐white race/ethnicity (African American OR = 1.8 [95% CI 1.3, 2.5], Hispanic OR = 2.3 [95% CI 1.6, 3.2]), and gender (male OR = 2.1, [95% CI 1.7, 2.5]). Gestational and birth characteristics associated with low cognitive function at 9 months included very low and moderately low birthweight (OR = 55.0 [95% CI 28.3, 107.9] and OR = 3.6 [95% CI 2.6, 5.1]), respectively, and very preterm and moderately preterm delivery (OR = 3.6 [95% CI 2.0, 6.7] and OR = 2.4 [95% CI 1.7, 3.5]), respectively, but they had weaker effects by 24 months (ORs for birthweight: 3.7 [95% CI 2.3, 5.9] and 1.8 [95% CI 1.4, 2.3]; ORs for preterm: 1.8 [95% CI 1.1, 2.9] and 0.9 [95% CI 0.7, 1.3]). Results for multiple births were similar. Sociodemographic disparities in poor cognitive functioning emerged by 24 months of age, but were not mediated by gestational or birth characteristics. Further investigation of processes whereby social disadvantage adversely affects development prior to 24 months is needed.     

Maternal and birth characteristics in relation to childhood leukaemia

Our objective was to investigate the association of childhood leukaemia with selected maternal and birth characteristics by conducting a population-based case-control study using linked cancer registry and birth certificate records for Washington State. We compared maternal and infant characteristics of 595 Washington-born residents <20 years old with leukaemia diagnosed during 1981-2003, and 5,950 control children, using stratified analysis and logistic regression. Maternal age 35+ years (odds ratio [OR] 1.5; 95% confidence interval [CI] 1.1, 2.0), infant birthweight 4,000+ g (OR 1.4; 95% CI 1.1, 1.8), neonatal jaundice (OR 1.5; 95% CI 1.1, 2.1), and Down's syndrome (OR 31.3; 95% CI 6.4, 153.4) were associated with an increased risk of leukaemia. Among women with 2+ pregnancies, having at least two prior early (<20 weeks' gestation) fetal deaths was also associated with an increased risk (OR 1.5; 95% CI 0.97, 2.1). Maternal unmarried status (OR 0.7; 95% CI 0.6, 0.9) and African American race (OR 0.5; 95% CI 0.3, 0.9) were associated with a decreased risk. These results were more marked for acute lymphocytic leukaemia (ALL) than for acute myeloid leukaemia (AML), and for leukaemia diagnosed <5 years of age. These results may provide clues to the aetiology of childhood leukaemia. Genetic epidemiological studies are needed to expand our knowledge of inherent and possibly prenatal influences on the occurrence of this disease.     

Perinatal risk factors for infantile autism

BACKGROUND: Etiologic hypotheses in infantile autism suggest a strong genetic component, as well as possible environmental risks linked to early fetal development. We evaluated the association of maternal, pregnancy, delivery, and infant characteristics and risk of infantile autism. METHODS: We conducted a case-control study nested within a population-based cohort (all Swedish children born in 1974-1993). We used prospectively recorded data from the Swedish Birth Register, which were individually linked to the Swedish Inpatient Register. Cases were 408 children (321 boys and 87 girls) discharged with a main diagnosis of infantile autism from any hospital in Sweden before 10 years of age in the period 1987-1994, plus 2,040 matched controls. Conditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: The risk of autism was associated with daily smoking in early pregnancy (OR = 1.4; CI = 1.1-1.8), maternal birth outside Europe and North America (OR = 3.0; CI = 1.7-5.2), cesarean delivery (OR = 1.6; CI = 1.1-2.3), being small for gestational age (SGA; OR = 2.1; CI = 1.1-3.9), a 5-minute Apgar score below 7 (OR = 3.2, CI = 1.2-8.2), and congenital malformations (OR = 1.8, CI = 1.1-3.1). No association was found between autism and head circumference, maternal diabetes, being a twin, or season of birth. CONCLUSIONS: Our findings suggest that intrauterine and neonatal factors related to deviant intrauterine growth or fetal distress are important in the pathogenesis of autism.     

Maternal risk factors and major associated defects in infants with Down syndrome

More than 50% of infants with Down syndrome have associated defects that cause considerable morbidity and mortality. We evaluated the hypothesis that the trisomic genome interacts with environmental factors to increase the risk for specific associated defects. We evaluated risk factors present during early pregnancy in a multiracial population of 687 infants with Down syndrome. Mother's cigarette smoking was associated with the grouped cardiac defects [odds ratio (OR)=2.0; 95% confidence interval (CI) = 1.2-3.2]. When adjusted for other cardiac defects and maternal race, the following specific defects were associated with smoking: atrioventricular canal (OR = 2.3; 95% CI = 1.2-4.5), tetralogy of Fallot (OR = 4.6; 95% CI = 1.2-17.0), and atrial septal defects without ventricular septal defect (OR = 2.2; 95% CI = 1.1-4.3). Hirschsprung disease was associated with mother's daily consumption of more than three cups of coffee (OR = 6.02; 95% CI = 1.2-29.7) and with mother's fever (OR = 3.4; 95% CI = 0.7-16.4), but the number of cases was small. Use of alcohol was not associated with any defect. Mother's race, age, parity, income, or education did not confound the associations. Results suggest that environmental factors can modify the occurrence of associated anomalies in the embryo with Down syndrome.     

Social determinants of birthweight and length of gestation in Estonia during the transition to democracy

BACKGROUND: To investigate social variation in birthweight and length of gestation in Estonia in the period of transition to a democracy and market economy. METHODS: All live births resulting from singleton pregnancies reported to the Estonian Medical Birth Registry in 1992-1997 (n = 84, 629) were studied with respect to social variation in birthweight and preterm delivery (<37 weeks gestation). The results were adjusted for maternal age, parity, education, nationality, marital status, smoking in pregnancy, sex of the infant (and gestational age). RESULTS: Between 1992 and 1997, mean birthweight increased from 3,465g to 3,497g (P < 0.001) and the preterm rate fell from 5.8% to 5.1% (P = 0.001). Maternal education, marital status and nationality were all independently related to the mean birthweight and the risk of preterm birth. The mean difference in birthweight between children of mothers with basic and university education was 87 g (95% CI : 74-100). Children born to mothers of non-Estonian compared to Estonian nationality were on average 77 g lighter (95% CI: 70-84). While the effect of nationality and marital status on birthweight was relatively stable during the study period, differences in birth outcome by maternal education became stronger. CONCLUSIONS: The mean birthweight increased and the preterm rate decreased in Estonia as a whole during the transition. However, the improvements were not shared equally by all social groups. An increase in variation in birthweight by maternal education was particularly notable.     

Factors Associated with Prenatal Smoking Among Black Women in Eastern North Carolina

Objectives: The objective of this research was to explore prenatal smoking behaviors among Black women attending prenatal clinics. Despite the racial disparities in poor pregnancy outcomes, and the well-known association of smoking with harmful outcomes, little research has been conducted about prenatal smoking among Black women. Methods: Women were enrolled in the study and interviewed at the time of the first prenatal visit. The interview contained items to assess prenatal smoking and cessation, depressive symptoms, demographic factors, and beliefs about smoking. Reports of smoking cessation were verified using urinary cotinine. Results: The sample consisted of 811 Black women. Fourteen percent of the women were self-reported smokers, 12.6% reported cessation and 73% were nonsmokers. Twenty percent of the self-reported quitters had elevated cotinine; when these women were reclassified, 17% of the women were smokers. Factors associated with smoking in logistic regression analysis included elevated maternal depressive symptoms (OR = 1.7, 95% CI: 1.1–2.6), maternal age 20 years or older (OR = 1.94; 95% CI: 1.1, 3.3), less than a high school education (OR = 2.2; 95% CI: 1.2, 3.8), unmarried/not living with a partner (OR = 1.9; 95% CI: 1.0, 3.6), and allowing smoking in the home (OR = 5.5; 95% CI: 3.4, 8.6). Conclusions: The prevalence of maternal prenatal smoking was much higher among women in this sample than has been previously reported. The rate of nondisclosure of smoking among self-reported quitters was also high. Maternal behavioral (allowing smoking in the home) and psychosocial factors (depressive symptoms) were associated with prenatal smoking.     

Prenatal tea consumption and risks of anencephaly and spina bifida

PURPOSE: To evaluate the relationship between prenatal tea consumption and risk of anencephaly and spina bifida.METHODS: Data from the population-based Atlanta Birth Defects Case-Control Study were examined. Cases were infants with anencephaly (n = 122) or spina bifida (r = 154) and no other associated anomalies, and identified between 1968 and 1980. Controls were infants without birth defects (n = 3029) identified from birth certificates of the same birth cohort and frequency matched to cases by race, period of birth, and hospital of birth.RESULTS: Maternal tea consumption during the periconceptional period (3 months before through the first trimester of pregnancy) was reported at 82, 83.6, and 92.9% among controls, anencephaly, and spina bifida cases, respectively. With subjects whose mothers consumed no tea as a reference, odds ratios (OR) for tea consumption during the periconceptional period (adjusted for gender, race, period of birth, maternal age, education, alcohol consumption, smoking, and periconceptional multivitamins) were: anencephaly 0.9 (95% confidence limits (CI) 0.5-1.5); spina bifida 2.3 (CI 1.2-4.4). Odds ratios for spina bifida and number of cups of tea consumed/day were: 1-2 cups 2.1 (CI 1.1-4.0); 3+ cups 2.8 (CI 1.4-5.6). Consumption of other caffeinated beverages was not associated with risk for anencephaly or spina bifida.CONCLUSIONS: Further studies are warranted to corroborate and elucidate the observed association between tea consumption and spina bifida.     

Chronic hypertension, cigarette smoking, and abruptio placentae.

We investigated the importance of maternal hypertension and cigarette smoking, and their interaction, as risk factors for abruptio placentae, using Massachusetts birth certificate data for 1987-1988. We used multiple logistic regression procedures to model data from 943 abruptio placentae cases and 10,648 randomly selected births. Risk of abruption was associated with a history of chronic hypertension (adjusted OR = 2.3, 95% CI: 1.5-3.5) and cigarette smoking during pregnancy (adjusted OR = 1.7, 95% CI: 1.5-2.0). There was also evidence of interaction between chronic hypertension and cigarette smoking. The hypoxemia that results from exposure to cigarette smoke and the alterations in uterine blood flow that result from hypertension may lead to placental lesions that cause abruption.     

Plasma total homocysteine, pregnancy complications, and adverse pregnancy outcomes: the Hordaland Homocysteine study

BACKGROUND: Total homocysteine (tHcy) measured in serum or plasma is a marker of folate status and a risk factor for cardiovascular disease. OBJECTIVE: Our objective was to investigate associations between tHcy and complications and adverse outcomes of pregnancy. DESIGN: Plasma tHcy values measured in 1992-1993 in 5883 women aged 40-42 y were compared with outcomes and complications of 14492 pregnancies in the same women that were reported to the Medical Birth Registry of Norway from 1967 to 1996. RESULTS: When we compared the upper with the lower quartile of plasma tHcy, the adjusted risk for preeclampsia was 32% higher [odds ratio (OR): 1. 32; 95% CI: 0.98, 1.77; P for trend = 0.02], that for prematurity was 38% higher (OR: 1.38; 95% CI: 1.09, 1.75; P for trend = 0.005), and that for very low birth weight was 101% higher (OR: 2.01; 95% CI: 1.23, 3.27; P for trend = 0.003). These associations were stronger during the years closest to the tHcy determination (1980-1996), when there was also a significant relation between tHcy concentration and stillbirth (OR: 2.03; 95% CI: 0.98, 4.21; P for trend = 0.02). Neural tube defects and clubfoot had significant associations with plasma tHcy. Placental abruption had no relation with tHcy quartile, but the adjusted OR when tHcy concentrations >15 micromol/L were compared with lower values was 3.13 (95% CI: 1.63, 6. 03; P = 0.001). CONCLUSION: Elevated tHcy concentration is associated with common pregnancy complications and adverse pregnancy outcomes.     

Childhood asthma in Beijing,China: a population-based case-control study

China is the most populous country in the world. Few studies, however, have been conducted there to investigate the risk factors for childhood asthma. A population-based case-control study was conducted in Shunyi County, People's Republic of China, in January 1999 and March 2001 to investigate the issue. An increased risk of childhood asthma was associated with smoking by relatives in front of the mother while she was pregnant with the child (odds ratio (OR) = 1.3, 95% confidence interval (CI): 1.0, 1.6) and with smoking by relatives in front of the child (OR = 1.4, 95% CI: 1.1, 1.9). The risk increased with the increasing number of smokers and the total minutes of smoking by relatives in front of both the child and the mother while she was pregnant with the child. An increased risk was observed for use of coal for heating (OR = 1.5, 95% CI: 1.1, 1.9). Those who reported using coal for cooking without ventilation also had an increased risk (OR = 2.3, 95% CI: 1.5, 3.5). An increased risk was observed for those who reported having molds or fungi on the ceilings of their houses (OR = 1.8, 95% CI: 1.1, 2.9) or inside the child's room (OR = 1.8, 95% CI: 1.0, 3.2). An increased risk was also found for those having both a dog and a cat as pets (OR = 1.5, 95% CI: 1.0, 2.3) or for finding both cockroaches and rats inside their houses (OR = 1.8, 95% CI: 1.2, 2.8).     

Induced abortion and low birthweight in the following pregnancy

BACKGROUND: To examine whether induced abortion increases the risk of low birthweight in subsequent singleton live births. METHODS: Cohort study using the Danish Medical Birth Registry (MBR), the Hospital Discharge Registry (HDR), and the Induced Abortion Registry (IAR). All women who had their first pregnancy during 1980-1982 were identified in the MBR, the HDR, and the IAR. We included all 15,727 women whose pregnancy was terminated by a first trimester induced abortion in the induced abortion cohort and 46,026 women whose pregnancy was not terminated by an induced abortion were selected for the control cohort. All subsequent pregnancies until 1994 were identified by register record linkage. RESULTS: Low birthweight (<2500 g) in singleton term live births occurred more frequently in women with one, two, three or more previous induced abortions, compared with women without any previous induced abortion of similar gravidity, 2.2% versus 1.5%, 2.4% versus 1.7%, and 1.8% versus 1.6%, respectively. Adjusting for maternal age and residence at time of pregnancy, interpregnancy interval, gender of newborn, number of previous spontaneous abortions and number of previous low birthweight infants (control cohort only), the odds ratios (OR) of low birthweight in singleton term live births in women with one, two or more previous first trimester induced abortions were 1.9 (95% CI: 1.6, 2.3), and 1.9 (95% CI: 1.3, 2.7), respectively, compared with the control cohort of similar gravidity. High risks were mainly seen in women with an interpregnancy interval of more than 6 months. CONCLUSIONS: The findings suggest a positive association between one or more first trimester induced abortions and the risk of low birthweight in subsequent singleton term live births when the interpregnancy interval is longer than 6 months. This result was unexpected and confounding cannot be ruled out.     

Acquisition and carriage of meningococci in marine commando recruits

Meningococcal acquisition is a prerequisite for invasive disease. Three hundred and eleven male marine commando recruits were studied throughout 29 weeks of basic training to identify factors influencing meningococcal carriage and acquisition including troop number, season, smoking, respiratory infection, antibiotic usage and nasopharyngeal bacterial interference flora. A high carriage rate on entry to training (118/311, 37.9%) and subsequent sustained high rates of meningococcal acquisition were found. Of the potential factors examined, only active and passive smoking were found to be associated significantly with meningococcal carriage on entry. The association between active smoking and meningococcal carriage was dose-dependent, with odds ratios (OR) of 2.2 (95% CIs 1.0-4.8) and 7.2 (95% CIs 2.3-22.9) for light and heavy smokers respectively. Passive smoking predisposed independently to carriage (OR 1.8, 95% CIs 1.1-3.0). Active and passive smoking combined to give an attributable risk for meningococcal carriage of 33%. In contrast, despite a high and sustained rate of meningococcal acquisition in the study population, none of the risk factors investigated, including active smoking, was associated significantly with meningococcal acquisition. No cases of meningococcal disease occurred during the 16-month study period. Therefore smoking may increase the duration of meningococcal carriage rather than the rate of acquisition, consistent with the increased risk of meningococcal disease from passive as opposed to active smoking. Public health measures that reduce the prevalence of smoking should reduce the risk of meningococcal disease.     

Maternal smoking and congenital heart defects

The Swedish Child Cardiology Registry (CCR) and the Swedish Medical Birth Registry (MBR) were used to investigate a possible association between maternal smoking during pregnancy and congenital heart defects. Among 1,413,811 infants born in 1983–1996 with known smoking exposure in early pregnancy, 3384 infants with congenital heart defects were selected (458 term infants with persistent ductus arteriosus (PDA) identified from MBR or CCR, and 2926 infants with other heart defects, identified from CCR). After controlling for year of birth, maternal age, parity, and educational level, a weak, statistically significant association between all heart defects and maternal smoking was found (odds ratio (OR): 1.09; 95% confidence interval (CI): 1.01–1.19). When infants with isolated PDA were removed from the case group the significance disappeared (OR: 1.07; 95% CI: 0.98–1.17). For truncus abnormalities (OR: 1.23; 95% CI: 1.02–1.49), atrial septal defects (OR: 1.63; 95% CI: 1.04–2.57), and PDA (OR: 1.30; 95% CI: 1.05–1.62), a rather strong effect of maternal smoking was indicated. The increased OR for PDA remained when gestational duration and intrauterine growth was also controlled for. Further research based on independent data sets is needed to conclude whether the risk estimates for maternal smoking are true and truly differ between the groups. The classification system used (with 24 classes) is described in enough detail to permit a repetition of the study.     

Active and passive smoking during pregnancy and risk of central nervous system tumours in children

The effects of maternal active and passive smoking during pregnancy on childhood central nervous system (CNS) tumours were assessed in a population-based case-control study. The mothers of 244 children aged 0-15 years with CNS tumours and 502 control mothers were interviewed about their smoking habits. All families were resident in the region of Lombardy, Italy. Risk estimates were calculated by unconditional logistic regression, adjusted for age, sex and area of residence. Active smoking by the parents before pregnancy was not associated with increased risk of CNS tumours in the children. Active smoking by the mother during early pregnancy (approximately the first 5 weeks) was associated with a slightly increased risk of the child developing a CNS tumour (odds ratio [OR] 1.5 [95% CI 1.0, 2.3]). An increased risk of CNS tumours was found in the children of non-smoking mothers exposed regularly to tobacco smoke both in early pregnancy (OR 1.8 [95% CI 1.2, 2.6]) and in late pregnancy (OR 1.7 [95% CI 1.2, 2.5]). Although this study was retrospective, the results confirm our previous findings and suggest an association between the risk of developing CNS tumours in children and regular passive smoking by the mother during pregnancy.